Project 4 will test the hypothesis that CGG trinucleotide repeats in the FMRI gene, the most prevalent single gene disorder contributing to autism risk, influence susceptibility to non-dioxin-like (NDL) persistent organic pollutants (POPs) identified in Core 3 and pro-inflammatory cytokine profiles identified in Project 3 to predominate in plasma of women participating in the MARBLES study during pregnancy. A major advantage of the neurotypical and susceptible neuronal cell models to be used in our studies is that they originate from the same individual; thus, individual genetic background variation is excluded as a confounding variable. The specific aims are: Aim 1: Produce isoautosomal iPSC-derived neuronal precursor cells (NPCs) possessing a normal FMRI gene and NPCs possessing an active FMRI CGG repeat expansion in the mid-premutation, high-premutafion, and full-mutation (FXS) range. Aim 2: Identify morphological and functional differences between neuronal cultures with a normal FMRI acfive allele and neuronal cultures with an active FMRI CGG repeat expansion in the mid-premutation, high premutation, or full-mutation (FXS) range. Aim 2.1: Identify temporal differences the development of synchronized Ca2+ oscillafions, electrophysiological properties, mitochondrial bioenergefics and oxidative stress among genotypes. Aim 2.2: Determine how funcfional anomalies identified in Aim 2.1 influence Ca2+- dependent signaling pathways required for acfivity dependent dendrific growth, especially the CaMKl->CREB->Wnt and P13K->Akt->TSC1/2->mTOR signaling pathways. Aim 3: Define the spatiotemporal profile of neuropathological sequelae caused by exposures that mimic the gestational environment in mothers participating in the MARBLES study. Aim 3.1: Determine how exposures to individual congeners and complex mixtures that model the most abundant of PBDEs, PCBs, or perfluorinated compounds in maternal plasma alter the morphometric and funcfional outcomes measured in Aim 2. Identify crifical windows of susceptibility among genotypes. Aim 3.2: Determine how exposures to cytokine/chemokine profiles identified in maternal plasma influence the morphometric and functional outcomes measured in Aim 2. Aim 3.3: Determine whether exposures tested in Aim 3.1 and/or Aim 3.2 differentially alter epigeneflc signatures of global and gene specific (FOXP3, MeCP2, Dnmt3a) methylation among genotypes.